PROJECT SUMMARY- CORE The CORE diffraction and computation laboratory provides facilities to all members of the Yale Center for Structural Biology (CSB) for the investigation of macromolecular systems by X-ray crystallography, including computers for data reduction and analysis, solution light scattering equipment and a facility for freezing crystals. Three of the PIs on this application (Steitz, Xiong and Strobel) are major users of this facility and the research projects of one (Breaker) benefit significantly from the light scattering equipment and computers and importantly from the collaboration with the Steitz and Strobel labs on riboswitch structural studies. The staff of the CORE laboratory maintains and upgrades the CSB instrumentation, and assists users with data processing and analysis as well as structure solving. The CORE staff also maintains the CSB website, which is heavily used by structural biologists both inside and outside Yale. This invaluable resource provides its users with access to all the programs and data bases that are generally useful to structural biologists. The programs on the web site are upgraded as new releases appear, and documentation is provided for many of them to further assist users. The CORE laboratory not only provides facilities and staff to assist the CORE lab users with solving their diffraction and computation problems, but importantly it provides the environment and opportunity for the users to interact with and help each other face-to-face. This has proven to be extraordinarily important for learning, problem solving and creative thinking.